The present invention relates to a jolt control system for a drive system including a prime mover and an automatic transmission.
It is known to reduce a shift shock by momentarily altering the output torque of a prime mover which an automatic transmission is associated with. If the timing of the start and end of this change in the output torque of the prime mover fails to occur during a period beginning with the start and ending with the termination of the shift operation, this output torque change takes place outside the period where the shift operation progresses, such as before the start of the shift operation or after the termination or completion of the shift operation. This may cause a large shift shock or result in degraded driving performance.
U.S. Pat. No. 4,266,447 teaches the detection of the start and termination of a shift operation by monitoring the revolution speed of an output shaft of the prime mover. This known method requires a data map which a synchronizing speed value is taken from. This data map has to be designed to take due consideration of the situation where the vehicle speed changes during the shift operation or the situation where the wheel acceleration varies during the shift operation.
An object of the present invention is to provide a jolt control system which is improved such that the period of a shift operation is detected accurately under any circumstances.